Abstract:
Observations of massive stars - before they explode - provide direct
identification of SN progenitors. Such studies require the combination
of a deep, high-resolution image of the SN location, serendipitously
obtained before it exploded, with a precise localization of the SN
(after it exploded) to enable us to select the correct progenitor from
among the stars in the pre-explosion SN images. After decades of
effort, only nine SN progenitors have so far been detected (6 during the
last 5 years). About twice a year a nearby SN is discovered in an area
previously observed by HST. The few recent identifications were mainly
based on repeat HST post-explosion imaging for this purpose. A better
alternative for SN localization is now provided by laser-guide-star
assisted adaptive optics systems (LGS-AO), as we have initially
demonstrated using the Keck LGS system. Here, we propose to continue
our successful program (2006-2009) to use NIRI+ALTAIR in LGS mode to
localize nearby SNe and identify their progenitors. A minimal Gemini
allocation (1 hour) leveraged by superb archival HST data will provide
exciting results. With each additional progenitor identified and
studied, we move closer to a robust mapping of specific progenitors to
each SN class, a key to understanding the physics of these powerful
cosmic explosions.